Java使用Calendar类实现动态日历

package com.softeem.j2016.example;

import java.util.Calendar;

import java.util.Date;

import java.util.Scanner;

/**

  * 1.打印日历

  * 1.1当月总天数

  * 1.2当月第一天是周几

  * 2.周末用【】包裹

  * 3.当前日期加[*]

  * @author admin

  * 2021/7/23

  */

public class CalendarDemo {

     //获取一个日期实例

     static   Calendar c = Calendar.getInstance();

     public static void show( int year, int month){

         //获取当天日期

         Date today = new Date();

         //获取系统时间的年月日

         int y = today.getYear() + 1900 ;

         int m = today.getMonth() + 1 ;

         int d = today.getDate() ;

         c.set(Calendar.YEAR,year);

         c.set(Calendar.MONTH,month- 1 );

         //设置当前日历的日期为本月的第一天(7.1)

         c.set(Calendar.DAY_OF_MONTH, 1 );

         //获取当前字段所表示日历的可能具备最大值(本月总天数)

         int days = c.getActualMaximum(Calendar.DAY_OF_MONTH);

         //获取当月第一天是周几(7.1前面设置为本月第一天),周日=1;

         int week = c.get(Calendar.DAY_OF_WEEK)- 1 ;

         //如果当天是周日,则设置为7

         week = week == 0 ? 7 :week;

         //打印空格数

         System.out.printf( "%d月一共有%d天,1号是周%d\n" ,month,days,week);

         System.out.printf( "==========【%d】年【%d】月==========\n" ,year,month);

         System.out.println( "一\t二\t三\t四\t五\t六\t日" );

         System.out.println( "================================" );

         //计数器

         int count  = 0 ;

         //（输出空格）如果当天是星期四则说明有三个空格,需要循环三次，则week-1

         for ( int i = 0 ; i < week - 1 ; i++) {

             System.out.print( "\t" );

             count++;

         }

         for ( int i = 1 ; i <=days; i++) {

             count++;

             //根据日期的数值判断是否是周末,如果是则用"[]"包裹

             String date = (count % 7 == 6 || count % 7 == 0 )? "[" +i+ "]\t" :i+ "\t" ;

             //在当前日期前使用"*"标记

             date = (y == year && m == month && d == i)? "*" + date:date;

             //输出日期

             System.out.print(date);

             //达到七位则换行

             if (count% 7 == 0 ){

                 System.out.println();

             }

         }

     }

     public static void main(String[] args) {

         Scanner sc = new Scanner(System.in);

         System.out.println( "请输入年份" );

         int year = sc.nextInt();

         System.out.println( "请输入月份" );

         int month = sc.nextInt();

         show(year,month);

     }

}